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Mn-based catalysts have attracted significant attention in the field of catalytic research, particularly in NOx catalytic reductions and CO catalytic oxidation, owing to their good catalytic activity at low temperatures. In this review, we summarize the recent progress of Mn-based catalysts for the removal of NOx and CO. The effects of crystallinity, valence states, morphology, and active component dispersion on the catalytic performance of Mn-based catalysts are thoroughly reviewed. This review delves into the reaction mechanisms of Mn-based catalysts for NOx reduction, CO oxidation, and the simultaneous removal of NOx and CO. Finally, according to the catalytic performance of Mn-based catalysts and the challenges faced, a possible perspective and direction for Mn-based catalysts for abating NOx and CO is proposed. And we expect that this review can serve as a reference for the catalytic treatment of NOx and CO in future studies and applications. [ABSTRACT FROM AUTHOR]

In this study, Samarium (Sm) modification over Mn oxide biochar (BC)-based catalysts was synthesized and the activity of low-temperature selective catalytic reduction with NH 3 (LT NH 3 -SCR) of NO was measured. Varies in surface area and pore volume, structure, morphology, and surface chemistry of Sm-modified Mn/BC catalyst were investigated to analyze the effect of Sm on the physiochemical properties on catalyst. The Sm(0.2)-Mn/BC catalyst showed the highest NH 3 -SCR activity with the NO conversion of 85% at 200 °C and best N 2 selectivity in a broad temperature range of 75–250 °C. Doping with Sm species, Mn4+ + Mn3+/Mnn+ and O α /O β increased greatly, and the surface adsorbed oxygen were enhanced in Sm(0.2)-Mn/BC catalyst, which could promote the oxidation of NO, the NO conversion and N 2 selectivity. In addition, weak and medium acid increased markedly after the Sm species added on catalysts, causing more active sites for SCR reaction. The NH 3 -SCR reaction of Sm(0.2)-Mn/BC catalyst followed the L-H mechanism, and the generation of intermediate –NH 2 , NH 4 + species and the N x O y species were observed which played vital part in the LT NH 3 -SCR reaction. • Sm doping resulted in more active sites for SCR reaction. • Sm-modification could promote the oxidation of NO. • Sm-modification could increase both the De-NO x rate and the N 2 selectivity. • The NH 3 -SCR reaction followed the L-H mechanism. [ABSTRACT FROM AUTHOR]

In this study, the effect of different zinc salts (ZnCl2 and ZnSO4) on the deactivation of activated carbon(AC)‐based Mn−Ce catalysts and the poisoning mechanism of zinc salts on Mn−Ce/AC are comparatively studied. SEM, BET, XRD, XPS, H2‐TPR, NH3‐TPD and In‐situ DRIFT are used to characterize the physical and chemical changes of Mn−Ce/AC catalyst. The Selective Catalytic Reduction (SCR) activities of Mn−Ce/AC has a noticeable decline after loading zinc salts, and the highest NO conversion of Zn poisoning catalysts do not exceed 70 %. And the acid site is occupied by Zn2+ on the catalyst, which affects the chemical adsorption of NH3 and hinders the formation of the intermediate ‐NH2. Moreover, the decrease of Mn4+, reducibility of manganese oxide and acid sites are more serious on ZnC−Mn‐Ce/AC. Besides, loading ZnSO4 can improve the content of Ce3+ and Oβ on catalyst surface, which can mitigate the poisoning effects of ZnSO4 on Mn−Ce/AC catalyst. Hence, ZnCl2 displays a more serious poisoning effect on Mn−Ce/AC catalyst compared with ZnSO4. Then the probable mechanism model of ZnCl2 and ZnSO4 on Mn−Ce /AC catalyst is proposed and compared. [ABSTRACT FROM AUTHOR]

• Transition metal oxides loaded on CeO 2 -NPs catalyst were synthesized. • Mn-loading CeO 2 -NPs catalyst displayed the highest NO x conversion. • Mn-Ce catalyst showed higher oxygen vacancy than Cu-Ce and Fe-Ce catalysts. • Mn-Ce catalyst had more NH 4 + at Brønsted acid site and NH 3, ads at Lewis acid site. Ceria (CeO 2) was considered as one of the most promising catalysts due to its oxygen storage capacity and redox property. However, the low activity of CeO 2 catalyst in SCR reaction limited its further application on industrial processes. Transition metal (Mn, Cu and Fe) oxides were impregnated on nanopolyhedron CeO 2 (CeO 2 -NP) catalysts to investigate the SCR performance. The Mn-CeO 2 -NP catalyst displayed the highest NO x conversion (ca. 70% conversion at 300 °C), followed by the Cu-CeO 2 -NP catalyst (ca. 65% conversion at 300 °C) and then the Fe-CeO 2 -NP catalyst (ca. 45% conversion at 300 °C). The results of H 2 -TPR showed that Mn-CeO 2 -NP and Cu-CeO 2 -NP catalysts were more efficient in reducing hydrogen at lower temperature than that of Fe-CeO 2 -NP catalysts. Based on XPS measurements, it was determined that the O α /(O α +O β) ratio was Mn-CeO 2 -NP (ca. 65%)> Fe-CeO 2 -NP (ca. 59%)> Cu-CeO 2 -NP (ca. 55%) catalyst. It was also shown by Raman spectroscopy that the Mn-CeO 2 -NP catalyst had a higher concentration of oxygen vacancies than that of the Cu-CeO 2 -NP and Fe-CeO 2 -NP catalysts. Meanwhile, more Brønsted acid sites, Lewis acid sites, nitrate and nitrites species were found in the Mn-CeO 2 -NP catalyst as seen by in situ DRIFT spectra. [Display omitted] [ABSTRACT FROM AUTHOR]

• Al 2 O 3 promoted the catalytic activity of Pb-poisoning MC/AC catalyst effectively. • Redox property and surface acidity were inherent motivation of catalytic activity. • Both E-R and L-H pathways occurred on fresh and poisoned catalysts. • Possible mechanism model of Al 2 O 3 on anti-PbCl 2 over MC/AC catalyst was proposed. Lead salts, as a heavy metal species, caused serious damage for the activity and operation lifetime of SCR catalysts. Al-decorated Mn-Ce/AC catalyst was synthesized using the impregnation method to investigate the anti-Pb poisoning ability of Al 2 O 3 on Mn-Ce/AC catalyst. The addition of Al expressed a significant promotion on activity of MC/AC catalyst in both fresh and poisoned states. XRD analysis confirmed that Al oxide confined the crystallization of active MnO 2 over the poisoned catalysts, contributing to the dispersion of components. From the morphology, Al doping increased the aggregation of PbCl 2 , which released more active sites and further restrained the negative effect of PbCl 2. More abundant of Mn4+ and surface oxygen with adding Al was in favor of the redox circle and the activation of reactants. The enhanced surface acidity and redox property served as the chemical motivations for the anti-PbCl 2 ability of catalysts. In situ DRIFTS demonstrated that all catalysts followed both E-R and L-H pathways, and the E-R played a dominant role in the reaction activity. PbCl 2 did not change the reaction pathways but made the reaction more difficult to happen. Finally, a possible mechanism model of Al 2 O 3 on PbCl 2 resistance over MC/AC catalyst was proposed. The addition of Al oxide effectivity increased the surface-active sites on the surface of AMC/AC catalyst. And the enhanced surface acidity and redox property served as the inherent chemical motivations for the anti-Pb poisoning ability of AMC/AC catalyst, leading to the difference in reactivity of the intermediates. On this basis, the reaction of PAMC/AC catalyst was stronger than that of PMC/AC catalyst in both E-R and L-H pathways. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the poisoning effect of CaO on activated carbon (AC)-based Mn-Ce catalysts was discussed. Loading CaO inhibited the catalytic activity of the catalyst and the NO conversion of the catalyst decreased from 69.5% to 38.2% at 75 °C. The amount of MnO2 in AC surface decreased in the process of loading CaO, which was detrimental to the Selective Catalytic Reduction (SCR) performance of the catalyst. The change of manganese oxide form inhibited generation rate for the chemisorption oxygen and NO2, which was the most critical reason for the decrease of catalytic activity. Besides, loaded CaO entered into the pores of the catalyst, which led to the blockage of the pores and further resulted in the decrease of the Brunauer-Emmett-Teller (BET) surface area and total pore volume. It also destroyed the oxygen-containing functional groups and acid site on the surface of AC. All of these caused the deactivation of Mn-Ce/AC catalyst after loading CaO. [ABSTRACT FROM AUTHOR]

In this study, a series of K species or/and SO 2 poisoned Mn-Ce doped CuX (MCCX) catalysts were prepared from waste blast furnace slag (BFS), and the influence mechanism of K species or/and SO 2 poisoning on the catalysts in low-temperature NH 3 -SCR process was investigated. The results demonstrated that MCCX-KCl catalyst had poorer NO conversion than MCCX-K 2 O below 200 °C, and the co-existence of K species and SO 2 considerably inhibited NO conversion. Aggregation of the Cu active component might also be facilitated by co-poisoning with K species and SO 2. Furthermore, K species and SO 2 co-poisoned catalysts showed fewer isolated Cu2+ species and Mn4+ species than that of K-poisoned catalysts, indicating a decrease in active sites after the addition of SO 2. The co-effect of K 2 O/KCl and SO 2 species impaired the redox capacity and decreased the surface acidity than K-poisoned catalysts to a greater extent. Nevertheless, K-poisoning had little effect on the surface intermediates during SCR reaction process, and K-poisoned catalysts followed both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanism. However, MCCX-KCl-SO 2 and MCCX-K 2 O-SO 2 catalysts contained fewer nitrate species, indicating that the co-effect of K species and SO 2 impeded the reaction between NO + O 2 species and pre-NH 3 species, thereby resulting in poor low-temperature NH 3 -SCR activity. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, CuX zeolite supported Mn and/or Ce oxides catalysts were synthesized by combining ion exchange and impregnation methods, and the zeolite X was generated using blast furnace slag (BFS). Doping Mn-Ce oxides onto the CuX catalyst, which has excellent resistance to SO 2 +H 2 O, improved the catalyst's activity for NH 3 -SCR at lower temperature. In addition, electron transfer from Mn4+ to Ce3+ and Cu2+ was enhanced, and the concentration of isolated Cu2+ and chemisorbed oxygen species was higher in the Mn-Ce/CuX catalyst. Also, the Mn-Ce/CuX catalyst provided excellent SCR activity because of its high acid capacity, which allowed it to provide extra acid sites, and its high redox ability, which enhanced the re-oxidized and re-reduced cycles. Additionally, produced sulfates on the catalyst surface after SO 2 and H 2 O poisoning might occupy Cu2+ active sites and affect the SCR process by competing with acid sites, nitrate species and intermediates on the Mn-Ce/CuX catalyst. [Display omitted] • Mn or Ce/CuX catalysts were prepared successfully from blast furnace slag. • Effects of Cu sites and Mn-Ce addition on the properties of the catalyst were analyzed. • Relationship between the physicochemical properties and catalytic activities of the catalysts was revealed. • Mn-Ce/CuX catalyst had excellent low-temperature NH 3 -SCR activity and SO 2 or H 2 O resistance. [ABSTRACT FROM AUTHOR]

Lead salts poisoning was a great challenge for the catalysts application in selective catalytic reduction (SCR) reaction of NO x with NH 3 in stationary sources. Herein, several typical transition metal (Cu, Co and Zr) oxides modified Mn-Ce/AC catalysts were prepared by impregnation method, and the effects of Cu, Co and Zr doping on resistance PbCl 2 poisoning for the catalyst were investigated. The addition of three transition metal oxides improved the PbCl 2 resistance of Mn-Ce/AC catalyst and maintained excellent low-temperature denitrification activity of the catalyst. The lead resistance performance of the three metal oxides followed: Cu > Co > Zr oxides. The NO conversion of Cu-doping catalyst after PbCl 2 poisoning was only ca. 10% lower than that of fresh Mn-Ce/AC catalyst at 225 °C. Cu, Co and Zr doping could decrease the loss of specific surface area caused by poisoning, while Cu-doped catalyst showed lowest crystallinity of active components. Meanwhile, the contents of Mn4+ and chemisorbed oxygen in Cu-doped catalyst were higher than those in Co- or Zr-doped catalysts. Cu, Co and Zr doping improved the surface acidity and redox performance of the poisoned catalysts, with Cu-doped poisoned catalyst exhibiting nearly the same surface acidity and redox performance as the fresh Mn-Ce/AC catalyst. Furthermore, Cu doping could also improve NO adsorption and was in favor to the SCR process. Besides, in situ DRIFTS results showed that the catalytic reaction pathways of all the poisoned or modified catalysts were in accordance with both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms. Finally, a possible anti-PbCl 2 poisoning mechanistic model of (Cu, Co and Zr) oxides modified on Mn-Ce/AC catalyst was proposed. [Display omitted] • Cu-modified MC/AC catalyst showed best resistance to PbCl 2 poisoning. • Transition metal oxides alleviated damage of PbCl 2 to MC/AC structure. • Redox ability and acidity of PbCl 2 -poisoned catalyst were promoted by modifying. • NH 3 -SCR reaction on PbCl 2 -poisoned catalyst followed L-H and E-R mechanism. [ABSTRACT FROM AUTHOR]